Radio Canada photoAutomated vehicle licence-plate readers have rapidly become a must-have tool for police but the way the data is being shared has caused British Columbia's privacy watchdog to throw up a red flag.

Increasingly, police cruisers are equipped with infrared cameras that can read as many as 3,000 plates an hour and, linked automatically to a database in the patrol car's computer, tell officers if a vehicle is stolen or connected with a traffic violation or more serious crime.

Civil liberties advocates have always been leery of the technology's Big Brotherish aspects, such as its ability to note where people, or at least their cars, are at any given time.

Now, after an investigation, B.C. Privacy Commissioner Elizabeth Denham has recommended changes to the way the Victoria Police Department uses its system, the Globe and Mail reports. It would apply to other B.C. police departments as well.

Denham is calling for several changes, the Globe said, most importantly for a requirement that when plates do not produce any matches in the cruiser's on-board database, which is managed by the RCMP, the scan record must be deleted immediately.

The "daily scan record" includes personal information of every registered owner whose plate was scanned, whether they're suspected of anything or not. For now the record is transferred by Victoria police to the Mounties at the end of each shift for deletion by them.

"Non-hit data is personal information about the suspicionless activities of citizens — information that the police have no reason to believe relates to criminal activity. This information is not serving a law enforcement purpose and therefore, VicPD cannot disclose it to the RCMP," Denham said in a news release.

Denham said plate-reading systems, that has been in use for six years, should be modified to delete non-hit data immediately once the system concludes it doesn't match any suspected violations. Future use or disclosure of such data would not be authorized under B.C. law, she added.

"Law enforcement agencies have recently discussed retaining non-hit data," Denham said. "Collecting personal information for traffic enforcement and identifying stolen vehicles does not extend to retaining data on the law-abiding activities of citizens just in case it may be useful in the future."

"This data is transferred to the RCMP for the sole purpose of its destruction," said Graham in a statement reported by CBC News.

Graham said the system has been very successful in snagging prohibited drivers, uninsured vehicles and cars with invalid licence plates.

"In fact, recent deployments of the technology have resulted in the detection of violations in such numbers that it often exceeded our officers' ability to keep up with the volume of violations," he said.

In his statement, Graham said he "appreciates and values the commissioner's role in assessing the privacy impact that law enforcement tools have on the community," but the department "respectfully disagrees" with some parts of her report on how the plate-reading system works, the Globe said.

"For example, [the Victoria Police Department] does not make known or reveal any non-hit data at any time," Graham said.

Supt. Denis Boucher, head of the B.C. RCMP's traffic-services section, confirmed that data not linked to a crime is deleted once it's transferred to the Mounties' server, The Canadian Press reported.

Boucher said the RCMP manages the data for all B.C. police departments, allowing them to have a single, secure database, CP said.

Graham dodged the question of whether his department would make the changes Denham is demanding. But Denham has the power to order compliance.

B.C. Attorney General Shirley Bond said she is reviewing the recommendations but indicated she supports limits on how data collected by the plate scanners is used.

"I don't support, without proper and appropriate protections in place, the expansion of the use of the technology," she told the Globe. "We've been clear about this: This technology is to take bad drivers off the road."